Today there is a growing need to provide controlled access and vessel management during such procedures as stenting, atherectomy or angioplasty. Generally, during these procedures there is a high opportunity for the release of embolic material. The emboli may travel downstream from the occlusion, lodging deep within the vascular bed and causing ischemia. The resulting ischemia may pose a serious threat to the health or life of a patient if the blockage forms in a critical area, such as the heart, lungs, or brain.
Several previously known methods and apparatus incorporate the use of an external suction system in conjunction with an aspiration catheter for removal of clots, removal of embolic particles, or general flow management in a vessel. However, there are several risks associated with using an external suction system during such medical interventions.
For example, if the amount of suction is too high, trauma may be imposed upon the vessel, resulting in vessel dissections or spasms. Additionally, an excessively high rate of aspiration may facilitate clot formation within the vessel. Moreover, if an external suction pump is utilized, excessively high aspiration rates may result in excessive blood loss, requiring infusion of non-autologous blood and raising related safety issues.
Traditional methods for regulating aspiration rates used with suction pumps have relied on external pressure adjustments, e.g., requiring physician monitoring of the suction rates, which may lead to an incorrect amount of suction for a given set of circumstances and present risk of the above-mentioned complications. Previously-known safety mechanisms, such as relief valves, have been employed and typically are coupled to the proximal end of the catheter. However, such features may require additional parts or assembly to regulate flow.
In view of these drawbacks of previously known systems, it would be desirable to provide apparatus and methods for self-regulating aspiration rates through a working lumen of a catheter to reduce trauma imposed upon a patient's vessel.
It also would be desirable to provide apparatus and methods that regulate aspiration rates using a mechanism that is an inherent feature of the catheter, to eliminate the need for continuous aspiration monitoring with the potential for human error.
It further would be desirable to provide apparatus and methods that reduce the likelihood of kinking when the catheter comprises a compliant member configured to regulate flow.
It still further would be desirable to provide apparatus and methods for self-regulating aspiration rates that may be tailored for use in specific applications, e.g., cerebral and cardiovascular interventions.